Special-purpose vehicles that are driven off-road usually have their engine space, including the cooling system, encapsulated to prevent vehicle failure due to damage to these components of the drive system from the penetration of foreign bodies. The engine is usually provided with combustion and cooling air through gratings. The engine spaces usually have two gratings to supply air to and remove it. A ventilator in the vicinity of the intake grating suctions in the requisite volumes of air. At the outlet grating the used air is allowed to flow out freely.
The specifications for such gratings usually include a large enough opening throughout the whole system to allow the requisite throughput of air and to create air channels, preventing the admission of foreign bodies.
The parallel strips of structural section known from German OS 3 703 716 are usually mounted in a frame. The ends of the individual strips of section are welded to associated components of the frame. The welds are accordingly exposed to impact and abrasion from the foreign bodies.
The welding produces areas of heat influx. The ballistic resistance of the sectional strips and frame components in these areas is lower than that of the material in general. It is also possible with this type of connection to ensure an intact weld between the frame components and the sectional strips.
An airborne-dust precipitator for engines or machinery is described in U.S. Pat. No. 3 970 439. Parallel sheets of foil are suspended in a frame. Mounting the edges of these sheets in slots or grooves in the sides of the frame is known from this patent. This known connection, however, cannot be used with gratings.